Despite the success of extensive AIDS prevention programs and powerful anti-retroviral drugs in limiting the spread of HIV-1 in high-income countries, it is generally agreed that for the developing world, these efforts will have to be combined with effective vaccines, but the design and testing of such vaccines have proven to be complex. It has been suggested that mucosal antibodies have an important role in preventing HIV-1 from crossing the epithelial barrier and ultimately in providing protection from infection. We propose to utilize fusion protein engineering and transgenic plants as a vaccine production platform in order to develop a mucosally-targeted subunit vaccine that provoke local and systemic immune responses against a broad range of HIV-1 subtypes to prevent the atraumatic sexual transmission of the virus. The main objective of this proposal centers on the development of such a candidate vaccine based on a fusion protein consisting of the mucosal-targeting B subunit of cholera toxin (CTB) and the conserved cerebroside (GalCer) binding domain (including the ELDKWA neutralizing epitope, a.a. 649-681, the "P1" peptide) of the HIV-1 gp41 envelope protein, which mediates the transcytosis of HIV-1 across the mucosal epithelia. The CTB-P1 chimera will be expressed in bacteria and in plant cells. We will then test its potential to elicit mucosal and systemic immune responses against HIV-1 in mice and assay the antibodies' capacity to neutralize transcytosis and infection. We believe that this new technology of plant-derived ("edible") vaccines emerging from the combination of immunology and plant genetic engineering has the potential to significantly impact the field of HIV/AIDS vaccine development in providing efficacious, cost-effective and safe (needle-free) vaccines. While it is probable that a single form of vaccination would not be effective in isolation, the plant-based vaccine may be combined with other types of vaccines in a prime/boost strategy.